01 the sdlc

The software development lifecycle How software is made

Success = on time + within budget + it works

Poor requirements are wildly expensive

Developers and customers must agree on requirements throughout the SDLC

Requirements Management involves

¡  Planning the SDLC ¡  Including how to gather requirements

¡ Controlling requirements changes ¡  including scope creep

¡  Tracking progress ¡ Negotiating requirements issues ¡  Periodic, formal reviews

The Software development lifecycle (SDLC) is marked by a trail of documents

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These documents outline the SDLC ¡  Project charter ¡  Functional Requirements ¡ Nonfunctional requirements ¡  Use Case Diagram ¡  Use Cases ¡ Activity Diagrams ¡ CRC Cards ¡  Sequence Diagrams ¡ Collaboration Diagrams ¡  State Diagrams ¡ Class Diagrams

The project charter ¡  The foundation

Functional requirements ¡ One-sentence description ¡ What the software should do

Nonfunctional requirements

¡ One-sentence description ¡  Parameters

The use case diagram ¡  Big-picture layout of all functionality ¡  How they relate to actors and to each other

Use cases ¡  Text narrative ¡ What the software

should do ¡ Not how to do it

Activity diagrams ¡ Visual representation of a use case ¡  Industry-standard nomenclature

CRC cards ¡ A tool to identify software objects!¡  Completely optional!

Sequence diagrams ¡ A tool to expose how the objects relate to one

another ¡  Emphasizes the order in which they relate

Collaboration diagrams ¡ A tool to expose how the objects relate to one

another ¡  Emphasizes the relationships, not the order

Class diagrams ¡  Extremely low-level design of the software

¡  The UML is the standard language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system

Several of these artifacts are created using UML

Conclusion ¡  Requirements list everything that the software

must do ¡  To get these wrong is to design bad software ¡  It is ridiculously expensive to discover bad

requirements late in the lifecycle ¡  The artifacts guide the SDLC and document its

history